This ProLF laser includes a 2.5" lens which is a good combination of cutting up to 1/4" and engraving details down to around 8pt fonts with a 90w tube. If you are requiring finer engraving and thin cutting such as fonts below 8pts, we recommend the 2" lens. The 2" lens has a good combination of fine engraving and thin cutting. A short focus lens has a smaller minimum spot size but spreads out more quickly after reaching the focus making them better for fine detail but not good for thick cutting. A long focus lens keeps the focus longer allowing for straighter edges but does not focus down to as small a minimum spot.